This invention relates generally to means for protecting human eyes from laser radiation, and, more particularly, to variable neutral density laser goggles.
The application of these goggles is to protect the wearer's eyes from intense radiation scattered or reflected from optical elements in the beam path of laser or other optical systems utilizing extremely bright light sources. They are not intended for direct viewing of laser beams. In the past, protection from laser radiation of a given wavelength was adequately provided for by laser goggles having filters therein that selectively removed the given wavelength of laser radiation. These goggles are so effective that one is almost unable to see the laser beam when it is reflected off an opaque surface.
A problem arises when one tries to align optical elements or focus beams using the actual laser beam with the above laser goggles. If one is hardly able to see the beam, alignment or focusing is almost impossible and one has the unsafe urge to remove the laser goggles. One answer to this problem is the stacking of neutral density filters. This method of removing or adding filters is inconvenient, time consuming and may lead to dangerous errors in reducing the laser radiation to safe observable levels when the laser must be adjusted over a wide range of intensities.
In the case of carbon dioxide laser welding, the laser beam is invisible and only the area of interaction with the metals is visible because of heating. If one only wears laser goggles that filter out the dangerous invisible CO.sub.2 laser radiation but allows visible radiation to pass, one is hardly able to directly view the interaction area because of the high intensity of the visible radiation emitted. The answer to this problem in the past required the combination of an invisible laser radiation filter with stacking of neutral density filters to lower the intensity of visible radiation as well as remove the invisible laser radiation.
The present invention is directed toward providing variable neutral density laser goggles in which these undesirable characteristics are minimized.